New SQL Vulnerability Patched

A moderate vulnerability in the Microsoft Data Access Components could compromise security on SQL Server systems. The security bulletin issued by Microsoft about the issue late Wednesday is the third involving SQL Server in the last two weeks.

The vulnerability, discovered by David Litchfield of Next Generation Security Software Ltd., exists in MDAC versions 2.5, 2.6 and 2.7. "Even though MDAC ships as part of all versions of Windows, the vulnerability can only be exploited on SQL Servers," Microsoft's bulletin (MS02-040) notes. "Customers who are not using SQL Server do not need to take action, despite the fact that MDAC may be installed on their systems."

According to the bulletin, an attacker could submit a database query containing a specially malformed parameter. Depending on the code submitted by the attacker, such a buffer overrun attack could cause the server to fail or run code of the attacker's choice.

To execute the attack, a would-be attacker would need the ability to load and execute a database query on the server, which would require a server configuration strongly discouraged by Microsoft in the first place.